This invention relates to a method and apparatus for testing for the presence of microorganisms.
At the present time, it is necessary to perform sterility tests on samples of pharmacological compositions and apparatus to comply with federal regulations in the United States and similar regulations in other nations.
Any such testing procedure must prevent adventitious microbial growth transmitted to the article or composition being tested or to the substrate containing a test culture medium from the environment; otherwise the test results are invalid. Therefore, it is necessary to demonstrate that the proper precautions have been taken to exclude extraneous microorganisms throughout the test period.
When testing sterilized articles of such a size and shape as to permit complete immersion in 1000 ml of culture medium, the exterior of the device is cleansed with a suitable decontaminating agent and the access to the contents of the device must be made in a suitable aseptic manner. In the special instance of testing devices having a hollow tube, such as transfusion or infusion assemblies, e.g., a syringe having a needle, it is necessary to demonstrate that the contents of the syringe are sterile and that the outside surface of the needle which enters the patient also is sterile. In the prior art procedure, it is common practice to inject the contents of the syringe into a growth medium, remove the needle and immerse the needle also in a growth medium. Typically, for bacteria, a thioglycollate medium has been utilized which includes a resayurin additive to provide for color indication, and also agar to inhibit diffusion throughout the medium. A medium which is particularly useful for determining the presence of fungi is soybean-casein digest medium. Another medium which is utilized for this latter purpose is sabourin. The presently utilized technique for testing sterilized needles requires two weeks incubation time and increases the risk of hand contamination of the needle, thereby causing an excessive number of false positive tests. Obviously, false positive tests are undesirable, for example, since they require resterilization of the entire batch or product which increases the risk of ruining the batch or product. Also, this direct method is somewhat limited since it requires a specific volumetric to area ratio, in order to control the oxygenation of the medium, and these volumetric ratios are sometimes difficult to achieve in practice.
It would be highly desirable to provide a procedure for testing the contents of a syringe which also permits testing the inside and outside surface of a needle that may be associated with the syringe for microorganisms or which also permits testing the tip of the syringe nipple (for syringes without a needle) for microorganisms in a single step procedure. It would also be desirable to provide such a test which eliminates or minimizes the risk of hand contamination during the test procedure. Furthermore, it would be desirable to provide such a test which eliminates the requirement for accurately maintaining specific volumetric to area ratios within the medium.